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Software-Defined Systems & Virtualization

December 4, 2012

Karl Paulsen

Of the many components
found in
a media-centric
operating environment,
storage might be categorized
as one of the more
evolving systems in the
overall architecture. As
administrators attempt
to sort out the directions
and requirements for their organization’s
expanding needs, technological approaches
continue to change, and so do the means
and methods of storage provisioning.

Operators and system technology architects
often need to make a variety of
decisions when it comes to storage upgrades.
Continuing to support islands of
storage, file systems and arbitrary naming
conventions are no longer appropriate
when addressing incremental changes in
workflow, storage capacity, availability or
accessibility. Today, with geographically
diverse operations, resource sharing and
changing business objectives, operators
find that new storage models must be utilized
to meet the demands for productivity,
changes in workflow and requirements for
acquisition and distribution.

Storage systems now must address a
host of applications, databases (metadata
and transactional), operating systems and
platforms and file systems. In the data-centric
world, software models and business
applications are redefining foundational
architectures, moving them from a static to
a dynamic model. This shift from hardwarecentric
to software-centric environments,
often framed around virtualization, is finding
its way into both networks and storage
systems. In this model, software becomes
the characterization for how a system is
configured as opposed to the hardware
methods of switches, disk drives and controllers
of previous architectures.

VIRTUALIZATION
From a computing perspective, virtualization
is the creation of a virtual platform
(network, resource, operating system or
storage device) that is not an actual, i.e.,
dedicated or real, device. Software plays
an extremely important factor in virtualization,
enabling the abstraction of a system
or systems to extend beyond single purpose,
singularly dedicated configurations.
For network systems this is referred to as
a “software-defined network” or SDN. For
storage systems, the industry has coined the
term “software-defined storage” (SDS).

Fig. 1: Through software-defined storage and virtualization, local operations can be protected even with differing storage architectures. The concepts can be leveraged at two physical datacenters within the same location or when located at differing remote sites. Virtualization allows for the applications and the operating systems at Site #1 to failover to Site #2 even though server clusters and storage system make ups are different.

At the root level, compute-systems perform
basic tasks based around their operating
system (OS). For example, applications
running on a general purpose computer
depend upon the OS to be the interface
between devices such as keyboards, displays,
file-organization and file-tracking.
The OS becomes the traffic cop, i.e., the
communications chain among other peripheral
devices including storage and I/O.
Running more than one operating system
on the same device is a complex challenge,
usually requiring that only one OS is fully
functional at any given time. When multiple
operating systems are enabled to run
on the same hardware, the term is referred
to as “paravirtualization,” which is unlike
“full-virtualization,” where an entire system
is emulated. In the latter, the paravirtualization’s
management module is known as the
“hypervisor” or “virtual-machine-monitor,”
which operates with an operating system
modified to work in a virtual machine.

The analogies of SDN and SDS have
even gone to the extent that we now have
the “software-defined data center” which
combines storage, servers and networking
into a conglomerate that extends from the
physical boundaries out into the cloud. This
software-centric thinking is prevalent everywhere,
it’s just called by different names
and understood in varying concepts.

RESOURCE POOLS
Software-defined storage employs intelligent
software that abstracts and transforms
network switches, drive arrays, including
flash memory systems, and servers into
pools of resources, which are then mapped
and provisioned to the applications, hosts
and workflows of the organization or entity.
Through virtualization, automation and the
use of dynamic management toolsets, these
systems become more flexible, increasing
productivity levels and in turn optimizing
the application experience overall.

Physical and virtual disk configurations
arrange redundant SAN paths, synchronize
mirroring, manage caching, load balancing
and are an enabler of thin-provisioning, .
Pools of storage can be arranged in tiers,
ranging from very fast solid-state “hot”
memory through RAID sets of SATA drives
(as “warm storage”) and even into active
private clouds, cloud service providers or
as a “cold” storage archive. Hosts can be
managed over a range of operating systems
such as Windows, UNIX and Linux.

With the variant activities now prevalent
in enterprise-class systems, tracking
and metering performance becomes more
complicated and is critical to understanding
the efficiency of the servers, storage and
networks. Monitoring systems are common
in virtual environments. They observe, on
a tier-by-tier basis, system activity so as to
identify hot spots, such as when excessive
disk I/O operations occur. In this case, the
tools sets will then automatically load balance
disk blocks between the active drives
to prevent bottlenecks.

Infrastructure functions for like and
unlike devices are manageable from dashboards
that reveal how each host (operating
system) is attached to each tier of storage.
The dashboard shows in graphic form,
what is happening at an overview level so
administrators can then drill down to the
details to reveal where systems are being
overdriven, or through the use of trending
tools to diagnose how a bottleneck was
generated.

SDS and SDN approaches are gaining
popularity in the data center and computecentric
world; some in the media world feel
these concepts will work their way into the
media centric domain. Whatever opinion is
expressed, as virtualization gains momentum
we’ll need more toolsets and more
management abilities to keep these systems
going. Watch for more development in
software-defined systems in coming years.

Karl Paulsen (CPBE) is a SMPTE Fellow
and the chief technology officer at Diversified
Systems. Read more about other these
and other storage topics in his recent book
“Moving Media Storage Technologies.”
Contact Karl at kpaulsen@divsystems.com.